linux.git/drivers/pci/probe.c, branch v5.10.258

PCI: Initialize RCB from pci_configure_device()

2026-03-04T12:19:35+00:00

[ Upstream commit 1a6845aaa6de81f95959b380b45de8f10d6a8502 ]

Commit e42010d8207f ("PCI: Set Read Completion Boundary to 128 iff Root
Port supports it (_HPX)") worked around a bogus _HPX type 2 record, which
caused program_hpx_type2() to set the RCB in an endpoint even though the
Root Port did not have the RCB bit set.

e42010d8207f fixed that by setting the RCB in the endpoint only when it was
set in the Root Port.

In retrospect, program_hpx_type2() is intended for AER-related settings,
and the RCB should be configured elsewhere so it doesn't depend on the
presence or contents of an _HPX record.

Explicitly program the RCB from pci_configure_device() so it matches the
Root Port's RCB.  The Root Port may not be visible to virtualized guests;
in that case, leave RCB alone.

Fixes: e42010d8207f ("PCI: Set Read Completion Boundary to 128 iff Root Port supports it (_HPX)")
Signed-off-by: Håkon Bugge 
Signed-off-by: Bjorn Helgaas 
Link: https://patch.msgid.link/20260129175237.727059-2-haakon.bugge@oracle.com
Signed-off-by: Sasha Levin

PCI: Do not attempt to set ExtTag for VFs

2026-03-04T12:19:32+00:00

[ Upstream commit 73711730a1128d91ebca1a6994ceeb18f36cb0cd ]

The bit for enabling extended tags is Reserved and Preserved (RsvdP) for
VFs, according to PCIe r7.0 section 7.5.3.4 table 7.21.  Hence, bail out
early from pci_configure_extended_tags() if the device is a VF.

Otherwise, we may see incorrect log messages such as:

  kernel: pci 0000:af:00.2: enabling Extended Tags

(af:00.2 is a VF)

Fixes: 60db3a4d8cc9 ("PCI: Enable PCIe Extended Tags if supported")
Signed-off-by: Håkon Bugge 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Zhu Yanjun 
Link: https://patch.msgid.link/20251112095442.1913258-1-haakon.bugge@oracle.com
Signed-off-by: Sasha Levin

PCI/ACPI: Fix runtime PM ref imbalance on Hot-Plug Capable ports

2025-08-28T14:22:54+00:00

[ Upstream commit 6cff20ce3b92ffbf2fc5eb9e5a030b3672aa414a ]

pci_bridge_d3_possible() is called from both pcie_portdrv_probe() and
pcie_portdrv_remove() to determine whether runtime power management shall
be enabled (on probe) or disabled (on remove) on a PCIe port.

The underlying assumption is that pci_bridge_d3_possible() always returns
the same value, else a runtime PM reference imbalance would occur.  That
assumption is not given if the PCIe port is inaccessible on remove due to
hot-unplug:  pci_bridge_d3_possible() calls pciehp_is_native(), which
accesses Config Space to determine whether the port is Hot-Plug Capable.
An inaccessible port returns "all ones", which is converted to "all
zeroes" by pcie_capability_read_dword().  Hence the port no longer seems
Hot-Plug Capable on remove even though it was on probe.

The resulting runtime PM ref imbalance causes warning messages such as:

  pcieport 0000:02:04.0: Runtime PM usage count underflow!

Avoid the Config Space access (and thus the runtime PM ref imbalance) by
caching the Hot-Plug Capable bit in struct pci_dev.

The struct already contains an "is_hotplug_bridge" flag, which however is
not only set on Hot-Plug Capable PCIe ports, but also Conventional PCI
Hot-Plug bridges and ACPI slots.  The flag identifies bridges which are
allocated additional MMIO and bus number resources to allow for hierarchy
expansion.

The kernel is somewhat sloppily using "is_hotplug_bridge" in a number of
places to identify Hot-Plug Capable PCIe ports, even though the flag
encompasses other devices.  Subsequent commits replace these occurrences
with the new flag to clearly delineate Hot-Plug Capable PCIe ports from
other kinds of hotplug bridges.

Document the existing "is_hotplug_bridge" and the new "is_pciehp" flag
and document the (non-obvious) requirement that pci_bridge_d3_possible()
always returns the same value across the entire lifetime of a bridge,
including its hot-removal.

Fixes: 5352a44a561d ("PCI: pciehp: Make pciehp_is_native() stricter")
Reported-by: Laurent Bigonville 
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220216
Reported-by: Mario Limonciello 
Closes: https://lore.kernel.org/r/20250609020223.269407-3-superm1@kernel.org/
Link: https://lore.kernel.org/all/20250620025535.3425049-3-superm1@kernel.org/T/#u
Signed-off-by: Lukas Wunner 
Signed-off-by: Bjorn Helgaas 
Acked-by: Rafael J. Wysocki 
Cc: stable@vger.kernel.org # v4.18+
Link: https://patch.msgid.link/fe5dcc3b2e62ee1df7905d746bde161eb1b3291c.1752390101.git.lukas@wunner.de
[ Adjust surrounding documentation changes ]
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

PCI: Fix reference leak in pci_register_host_bridge()

2025-05-02T05:41:14+00:00

[ Upstream commit 804443c1f27883926de94c849d91f5b7d7d696e9 ]

If device_register() fails, call put_device() to give up the reference to
avoid a memory leak, per the comment at device_register().

Found by code review.

Link: https://lore.kernel.org/r/20250225021440.3130264-1-make24@iscas.ac.cn
Fixes: 37d6a0a6f470 ("PCI: Add pci_register_host_bridge() interface")
Signed-off-by: Ma Ke 
[bhelgaas: squash Dan Carpenter's double free fix from
https://lore.kernel.org/r/db806a6c-a91b-4e5a-a84b-6b7e01bdac85@stanley.mountain]
Signed-off-by: Bjorn Helgaas 
Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin

PCI: Assign PCI domain IDs by ida_alloc()

2025-05-02T05:41:14+00:00

[ Upstream commit c14f7ccc9f5dcf9d06ddeec706f85405b2c80600 ]

Replace assignment of PCI domain IDs from atomic_inc_return() to
ida_alloc().

Use two IDAs, one for static domain allocations (those which are defined in
device tree) and second for dynamic allocations (all other).

During removal of root bus / host bridge, also release the domain ID.  The
released ID can be reused again, for example when dynamically loading and
unloading native PCI host bridge drivers.

This change also allows to mix static device tree assignment and dynamic by
kernel as all static allocations are reserved in dynamic pool.

[bhelgaas: set "err" if "bus->domain_nr < 0"]
Link: https://lore.kernel.org/r/20220714184130.5436-1-pali@kernel.org
Signed-off-by: Pali Rohár 
Signed-off-by: Bjorn Helgaas 
Stable-dep-of: 804443c1f278 ("PCI: Fix reference leak in pci_register_host_bridge()")
Signed-off-by: Sasha Levin

PCI: Coalesce host bridge contiguous apertures

2025-05-02T05:41:14+00:00

[ Upstream commit 65db04053efea3f3e412a7e0cc599962999c96b4 ]

Built-in graphics on HP EliteDesk 805 G6 doesn't work because graphics
can't get the BAR it needs:

  pci_bus 0000:00: root bus resource [mem 0x10020200000-0x100303fffff window]
  pci_bus 0000:00: root bus resource [mem 0x10030400000-0x100401fffff window]

  pci 0000:00:08.1:   bridge window [mem 0xd2000000-0xd23fffff]
  pci 0000:00:08.1:   bridge window [mem 0x10030000000-0x100401fffff 64bit pref]
  pci 0000:00:08.1: can't claim BAR 15 [mem 0x10030000000-0x100401fffff 64bit pref]: no compatible bridge window
  pci 0000:00:08.1: [mem 0x10030000000-0x100401fffff 64bit pref] clipped to [mem 0x10030000000-0x100303fffff 64bit pref]
  pci 0000:00:08.1:   bridge window [mem 0x10030000000-0x100303fffff 64bit pref]
  pci 0000:07:00.0: can't claim BAR 0 [mem 0x10030000000-0x1003fffffff 64bit pref]: no compatible bridge window
  pci 0000:07:00.0: can't claim BAR 2 [mem 0x10040000000-0x100401fffff 64bit pref]: no compatible bridge window

However, the root bus has two contiguous apertures that can contain the
child resource requested.

Coalesce contiguous apertures so we can allocate from the entire contiguous
region.

[bhelgaas: fold in https://lore.kernel.org/r/20210528170242.1564038-1-kai.heng.feng@canonical.com]
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212013
Suggested-by: Bjorn Helgaas 
Link: https://lore.kernel.org/r/20210401131252.531935-1-kai.heng.feng@canonical.com
Signed-off-by: Kai-Heng Feng 
Signed-off-by: Bjorn Helgaas 
Stable-dep-of: 804443c1f278 ("PCI: Fix reference leak in pci_register_host_bridge()")
Signed-off-by: Sasha Levin

PCI: Introduce domain_nr in pci_host_bridge

2025-05-02T05:41:13+00:00

[ Upstream commit 15d82ca23c996d50062286d27ed6a42a8105c04a ]

Currently we retrieve the PCI domain number of the host bridge from the
bus sysdata (or pci_config_window if PCI_DOMAINS_GENERIC=y). Actually
we have the information at PCI host bridge probing time, and it makes
sense that we store it into pci_host_bridge. One benefit of doing so is
the requirement for supporting PCI on Hyper-V for ARM64, because the
host bridge of Hyper-V doesn't have pci_config_window, whereas ARM64 is
a PCI_DOMAINS_GENERIC=y arch, so we cannot retrieve the PCI domain
number from pci_config_window on ARM64 Hyper-V guest.

As the preparation for ARM64 Hyper-V PCI support, we introduce the
domain_nr in pci_host_bridge and a sentinel value to allow drivers to
set domain numbers properly at probing time. Currently
CONFIG_PCI_DOMAINS_GENERIC=y archs are only users of this
newly-introduced field.

Link: https://lore.kernel.org/r/20210726180657.142727-2-boqun.feng@gmail.com
Signed-off-by: Boqun Feng 
Signed-off-by: Lorenzo Pieralisi 
Acked-by: Bjorn Helgaas 
Stable-dep-of: 804443c1f278 ("PCI: Fix reference leak in pci_register_host_bridge()")
Signed-off-by: Sasha Levin

PCI: Fix reference leak in pci_alloc_child_bus()

2025-05-02T05:40:57+00:00

commit 1f2768b6a3ee77a295106e3a5d68458064923ede upstream.

If device_register(&child->dev) fails, call put_device() to explicitly
release child->dev, per the comment at device_register().

Found by code review.

Link: https://lore.kernel.org/r/20250202062357.872971-1-make24@iscas.ac.cn
Fixes: 4f535093cf8f ("PCI: Put pci_dev in device tree as early as possible")
Signed-off-by: Ma Ke 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Ilpo Järvinen 
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman

PCI: Remove stray put_device() in pci_register_host_bridge()

2025-04-10T12:30:56+00:00

[ Upstream commit 6e8d06e5096c80cbf41313b4a204f43071ca42be ]

This put_device() was accidentally left over from when we changed the code
from using device_register() to calling device_add().  Delete it.

Link: https://lore.kernel.org/r/55b24870-89fb-4c91-b85d-744e35db53c2@stanley.mountain
Fixes: 9885440b16b8 ("PCI: Fix pci_host_bridge struct device release/free handling")
Signed-off-by: Dan Carpenter 
Signed-off-by: Bjorn Helgaas 
Signed-off-by: Sasha Levin

Revert "PCI: Use preserve_config in place of pci_flags"

2025-02-01T17:22:30+00:00

This reverts commit 0dde3ae52a0dcc5cdfe2185ec58ec52b43fda22e which is
commit 7246a4520b4bf1494d7d030166a11b5226f6d508 upstream.

This patch causes a regression in cuttlefish/crossvm boot on arm64.

The patch was part of a series that when applied will not cause a regression
but this patch was backported to the 5.10 branch by itself.

The other patches do not apply cleanly to the 5.10 branch.

Signed-off-by: Terry Tritton 
Signed-off-by: Greg Kroah-Hartman